Nuclear space hopper an option for Mars

Small rovers that hop from place to place are being developed for future Mars missions. Powered by nuclear energy, they could map the entire planet in a few years.

The idea is under development at Idaho National Laboratory's Centre for Space Nuclear Research (CSNR).

When stationary the vehicles would study the area around them, slowly sucking up carbon dioxide from the atmosphere and freezing it. When the time comes for the next hop, nuclear heat would rapidly vaporise the carbon dioxide, creating a powerful jet to propel the craft up to 1000 metres into the air.

All power would come from radioisotope thermoelectric generators (RTGs), which use steady heat from radioactive decay to drive a Stirling engine for compression of gas and generation of electricity for on-board sensors. Meanwhile a beryllium core would efficiently store up heat energy required for the explosive vaporisation needed for the next hop.

"Nuclear energy is the enabling technology. The isotope allows you to keep doing this for years," said Robert O'Brien, a CSNR research scientist.

(Image: INL)

A small hopper could cover 15 kilometres at a time, repeating this every few days over a ten year period. By comparison, the two large solar powered rovers that landed on Mars in 2004 have between them covered only 34 kilometres.

A range of hoppers are possible to carry scientific payloads between 10 kilograms and 200 kilograms - all able to travel long distances and hop into and out of craters. "They're small, they're cheap, and therefore you can risk the nooks and crannies," said the CNSR's Steven Howe. "If you find a crevice that might have water coming from underneath the surface – then the hopper can get down there."

A few dozen hoppers could map the Martian surface in a few years, said INL, and it's even possible that a fleet could convey rock samples from all over the Martian surface to a craft that would bring them to Earth.

Researchers from University of Idaho, Utah State and Oregon State University are contributing to CSNR hopper development, as are other US national labs and of course NASA.